Fibroblast　activation　protein-alpha　(FAPα)　is　a　type-II　integral　membrane　serine　protease　and　is　expressed　in　most　stromal　fibroblasts.　Recent　studies　showed　that　FAPα　is　also　expressed　in　certain　cancer　cells　but　its　role　is　still　uncertain.We　analyzed　the　non-enzymatic　activity　of　FAPα　in　breast　cancer　cells　by　introducing　an　enzymatic　mutant　FAPα　(FAPS624A),　in　which　the　serine　catalytic　triad　was　destroyed.　FAPα　overexpression　and　knockdown　cells　were　generated　as　controls.Cellular　growth　and　motility　were　markedly　increased　in　MCF-7　cells　overexpressing　FAPα　and　enzymatic-mutant　FAPS624A.　This　is　consistent　with　observations　in　FAPα-silenced　BT549　cells.　Western　blotting　showed　activation　of　phosphatidylinositol-3-kinase　(PI3K)/protein　kinase　B　(AKT)　and　matrix　metalloproteinase　(MMP)　2/9　in　both　wild-type　FAPα-overexpressing　and　enzymatic-mutant　FAPS624A-overexpressing　cells.Promotion　of　cellular　growth　and　motility　is　independent　of　the　enzymatic　activity　of　FAPα　in　breast　cancer　cells.　The　PI3K/AKT　and　MMP2/9　signaling　pathways　might　be　involved　in　such　regulation.